Osananajimi Yuka -Yuujin ni Zecchoo Kairaku o Kizamitsukerarete Iku Motokano Osananajimi | 幼馴染み・結花 ～友人に絶頂快楽を刻みつけられていく元カノ幼馴染み～

Koji Ihama and Yuka Suzueda are childhood friends who were also lovers several times in the past. However, they repeatedly broke up after getting together, and the last time, even after having a physical relationship, they couldn't overcome the feeling that their relationship was wrong and realized they couldn't be lovers, leading to their breakup. They thought they could never go back to being just childhood friends.

After moving to Tokyo together for college, they grew closer again and became like their old selves, often spending time together as childhood friends. While feeling happy to be in a relationship they once thought lost and irretrievable, they decided they wouldn't be lovers and wanted to remain childhood friends.

One day, Koji's classmate, Hiroki Nakamo, confided in him that he liked Yuka. Knowing Hiroki was a good guy, Koji encouraged him to confess. Later, Yuka consulted Koji about Hiroki's confession, and he supported her as well. He couldn't be her lover anymore…

They started dating, vowing to continue their childhood friendship.

Even after learning about Yuka and Hiroki's physical relationship, Koji felt a disturbance within him, but could only deny that it was jealousy.

Eventually, Hiroki learned that Koji was Yuka's former lover and sensed Koji's lingering presence in Yuka's heart, fueling intense jealousy. To win Yuka's heart and body, Hiroki began to flaunt his physical relationship with Yuka to Koji…